Difficult diagnosis of fever of unknown origin related to an infraclinic liposarcoma: "small tumor and fever of unknown origin"

INTRODUCTION: Palpation of soft tissues constitutes part of the physical examination when faced with a patient with fever of unknown origin. Our case highlights the difficulty of diagnosis when the tumor still remains impalpable ten months after onset of fever and severe biological inflammatory process. EXEGESIS: A 49-year-old woman was admitted for fever of unknown origin associated with important biological inflammatory process. In view of her past medical history of breast carcinoma, a search for a relapse was performed and remained negative. Despite multiple investigations and repeated physical examinations, no diagnosis was obtained. Finally, [18F] fluorodoexyglucose positron emission tomography led to a diagnosis showing a high fixation located in the right thigh, related to a myxoid liposarcoma after surgical resection. CONCLUSION: Dramatic regression of fever and biological inflammatory process after surgical treatment illustrates the concept of "small tumor and fever of unknown origin", an exceptional entity but which physicians should be aware of. The role of new technical imaging with [18F] fluorodoexyglucose positron emission tomography has however to be clarified in the evaluation of fever of unknown origin.